Come valuta #cos ((2pi) / 3) #?
Risposta:
# -1/2#
Spiegazione:
The angle # (2pi)/3" is in the 2nd quadrant "#
where the cos ratio has a negative value.The related 'acute angle' to #(2pi)/3 =( pi -(2pi)/3) = pi/3 #
#rArr cos((2pi)/3) = - cos(pi/3) #
and using the #color(blue)" Exact value triangle"#
# cos((2pi)/3) = - cos(pi/3) = -1/2 #